HIGH MEM suport for up to 64GB

William Harman rfoster at lnxi.com
Sat Apr 20 10:22:15 EDT 2002


Sounds right.  __PAGE_OFFSET is set to 0xC0000000 by default, so
you get 3GB of address space for user processes.  And about 2GB
max for the data segment.

You can change the kernel to give you more than 3GB of address
space and greater than 2GB of data segment for heap allocations.
It's three lines to change. Two lines in header files and one
line in the one of the assembly init files.



Leandro Tavares Carneiro (leandro at ep.petrobras.com.br) wrote*:
>
>Hi everyone,
>
>	I am writing to ask to you all if anyone have tesed or used an machine
>with more than 4GB of RAM or paging in virtual memory on intel machines.
>	He have an linux beowulf cluster and one of ours developers have asked
>us for how much memory an process can allocate to use. In the tests we
>have made, we cannot allocate much more than 3GB, using an dual PIII
>with 1GB of ram and 12Gb of swap area for testing.
>	We can use 2 process alocating more or less 3Gb, but one process alone
>canot pass this test.
>	We have using redhat linux 7.2, kernel 2.4.9-21, recompiled with High
>Mem suport.
>	I have tested the same test aplication on an Itanium machine, with 1GB
>of ram and 16Gb of swap area, and they passed. The aplication can
>alocate more than 5GB of memory, using swap. In this machine, we are
>using turbolinux 7, with kernel version 2.4.4-010508-18smp.
>
>Thanks in advance for the help,
>
>Best regards,
>
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